They're replacement blades for the Tamiya Modeler’s Knife Pro (item 74098).
• Narrow Chisel blades x5
• 0.55 mm thick.
• Narrower than the currently available chisel blade (Item 74101, Width: 4mm), and hence may be used in tighter spaces.
• suited to the removal of protrusion from flat surfaces of ribs and molds an such like.